In the prior art various so-called "cruise-control" apparatus have been disclosed, utilizing various principles and of more or less complexity, examples being disclosed in these U.S. Patents:
No. 3,417,836 issued to R. H. Thornes on 12-24-68, showing an electro-mechanical apparatus for the purpose;
No. 3,104,741 issued to J. A. McDougal on 9-24-63, showing a vacuum-associated device for the purpose;
No. 1,218,028 to V. A. Williams, 3-6-17, showing rack and pawl apparatus with straight bar rack in one embodiment and segmental rack in another, and co-acting pawl mechanism controllable from the steering column.